MobileMonet, an artistic iPhoneography app, has dropped in price to £0.69

Made by the same guys, East Coast Pixels, that made some other hugely popular apps like Photo Toaster and Color Blast!, this is a good fun app to transform your photos into colored sketches. Colors can be filled in selectively and progressively. You also get options to change the intensity of vibrance, brightness and color.

I personally preferred using this app for landscapes rather than portraits. A good app overall - recommended.